Adjustable jet propulsion nozzle for gas turbines



22580 $33 3:35 kma f N wx i N 1 ll s I w w 2 m m m m n m T n H N u 7 mmW H m z M A w 2 aw Ema u mm 3?; M w m. zocfiom RD N N lozzgoo 3: 3 I1-0515 u u Aug. 1, 1950 A. H. REDDING ETAL ADJUSTABLE JET PROPULSIONNOZZLE FOR GAS TURBINES Filed Sept. 17, 1947 Patented Aug. l, 1950ADJUSTABLE JET PROPULSION NOZZLE FOR GAS TURBINES Arnold H. Bedding,Swarthmore, Pa., and David W. Hutchinson, Mamaroneck, N. Y., assiznor toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Application September 17, 1947, SerlalNo. 774,480

1 Claim. 1

The invention relates to jet propulsion apparatus wherein motive fluidexhausting from a turbine through apropulsion nozzle is supplied to theturbine from a combustor furnished with fuel and supplied with air by acompressor driven by the turbine and it has for an object to provideimproved means for controlling the turbine speed and the thrust of thepropulsion jet to simplify control from the standpoint of the operator,to provide for rapid acceleration of the aircraft, and to assure of alower turbine inlet temperature at cruising or normal speeds, wherebythe life of the apparatus is prolonged.

The ordinary turbo-jet engine having a fixed nozzle exit area may havethe throttle lever provided with cams arranged so that the lever settinghas proportional relation to jet thrust.

The present invention involves a nozzle hav-- ing a movable component tovary the exit area and interconnection of the operating means thereforso that, with the component positioned to provide an area somewhatlarger than that giving full thrust at full engine speed, the engine orturbine is brought up to full speed and then, with the turbine or enginecontinuing to operate at full speed the nozzle component is moved toreduce the exit area to increase the jet thrust.

Accordingly, a more particular object of the invention is to provide jetpropulsion apparatus wherein the throttle lever has cams or the likearranged to operate speed control means for the turbine and exit areavarying means for the nozzle in sequence so that, with the nozzle exitarea somewhat larger than that for full thrust at full turbine speed,the turbine is first brought up to full speed and then, while continuingto operate at full speed, further movement of the throttle lever is usedto bring about adjustment of the nozzle to reduce the exit area toincrease the jet thrust.

The foregoing and other objects are effected by the invention as will beapparent from the following description and claim taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Figure 1 is a diagrammatic view showing a jet propulsion plant with theimproved control mechanism for the turbine and the propulsion jetnozzle;

Figure 2 is a diagrammatic development showing the relationship of camsurfaces operated by the throttle lever and the follower elements whichcooperate with the cam surfaces; and

Figure 3 is a diagram contrasting operation of (Cl. Gil-35.6)

2 the improved arrangement with that heretofore employed.

In the drawing, there is shown a turbo-jet plant, at It, including anaxial-flow compressor l2, a combustor arrangement It, a turbine I5,arranged in sequence between the forward air inlet l6 and thejet nozzle,at It.

Motive fluid exhausting from the turbine l5 passesthrough the nozzle, atI8, to form the propelling jet, and motive fluid is supplied to theturbine from the combustor or combustors M furnished with fuel andsupplied with air by gihelans of the compressor #2 driven by the tur-The turbine speed is controlled or regulated by varying the rate atwhich fuel is supplied to the combustors.

The thrust of the exhaust nozzle, at It, is

varied by axial adjustment of the movable component 2!) thereof; forexample, such movable component is shown as being constituted by anaxially movable tail cone 20, which is moved to and fro to vary the exitarea A by means of a lever 2 l To facilitate an understanding of thepresent unified control of engine speed and propulsion jet nozzle exitarea, reference is made to the conventional turbo-jet plant now in useand which has a fixed exit nozzle area. A throttle lever is usuallyprovided; and, by the selection of suitable cams the setting of suchlever may be made proportional to thrust; operation of the lever toincrease the thrust involving increasing the rate of fuel, or speed, asindicated by the dotted line b in Figure 3, while, at the same, thetemperature is increased as indicated by the dotted line 0. The presentinvention involves variation in exit area with the turbine operatingapproximately at full speed so that the thrust may be increased fromabout one-half of full thrust to full thrust merely by decreasing thenozzle exit area. According y, therefore, the present invention involvesinterrelating turbine speed and nozzle exit area so that, with the exitarea somewhat larger than that for full thrust at full turbine speed,the turbine speed is increased as indicated by the full line it inFigure 3, full speed being reached at e; and, with the turbine operatingat full speed the nozzle exit area is reduced, as indicated by the fullline between e and f. The line g shows that, with the improved controlarrangement, the turbine inlet temperature is lower throughout thethrust range, this feature contributing to longer life of the apparatus,

particularly when operating at cruising or normal speeds.

The turbine speed is regulated over a suitable range by mechanismincluding a governor 24 operated by mechanism including the takeoffshaft 25 driven by the turbine, the governor controlling the input offuel to the line 26 to the combustor or combustors H.

Any suitable means may be employed to move the lever 2| or the like forshifting the tail cone 20. By way of example, the lever 2| is shown asbeing connected to a link 21 having rack teeth 28 meshing with a pinion29 driven by a reversible electric motor 30, the motor having acontroller 3| equipped with a lever 32, the controller being constructedand arranged so that movement of the lever causes the motor to operatein one direction or the other, and it is so arranged that its travelfollows that of the controlling lever to maintain the proportionality asbetween the position of control lever 32 and the position of the tailcone 20.

As it is required that the turbine be brought up to full speed beforethe nozzle exit area is reduced, the controlling lever 32 of the motorcontroller and the speed adjusting means of the governor are operated,respectively, by rods 34 and 35, which cooperate with cams 36 and 31connected to the throttle lever 38 so that the cams adjust the governorand the motor controller in sequence. The arrangement is such that untilthe throttle lever 38 is brought to full speed position, the tail cone20 occupies a position such that the nozzle exit area A is somewhatlarger than that for full thrust at full turbine speed. The throttlelever is moved over a range to move the cam 36 to adjust the governor toincrease the fuel supply to increase the turbine speed to full speed,this operation being indicated by the line d in Figure 3; and, with theturbine operating at full speed, further movement of the throttle lever38 moves the cam 31 to control the motor to move the tail cone 20 so asto restrict the nozzle exit area, the area adjustment operation beingindicated by the line ein Figure 3.

Any suitable arrangement of cams or mechanism associated with thethrottle lever may be used to accomplish the purpose just indicated solong as the proper sequential operation is secured, the sequence beingclearer from a consideration of diagrammatic Figure 2, in which it willbe seen that, with the follower at the lower end of the hit portion 49of the cam 36, the follower 35 of the motor control lever will be inadvance of the lower end of the left portion 4! of the cam 37 of themotor controller a distance corresponding to the distance required tomove the follower for the turbine speed range, that is, when thefollower 34 reaches the maximum lift end of the cam surface 4!], thefollower 35 for the motor controller will be at the lower end of thelift surface ll of the cam 3'5; and, continued motion of the cams in thesame direction is efiective to hold the follower in the turbine fullspeed position while the follower 35 is moved to bring about movement ofthe tail cone to reduce the nozzle exit area, such area being reduced tothe minimum value when the follower reaches the maximum lift end of thecam surface 38.

From the foregoing, it will be apparent that we have improved control ofapparatus of the above character, made operation thereof in propellingaircraft safer and more reliable, and have provided for operation atlower turbine inlet temperatures particularly at normal or cruisingspeeds, thereby giving to the apparatus longer life. The sequentialoperations of increasing the turbine speed and of reducing the nozzleexit area may be effected by movement of a simple throttle lever in asingle direction. Safer and more reliable propulsion of aircraft issecured because change in thrust from one-half of full thrust to fullthrust is effected merely by adjusting the nozzle exit area, the speedbeing held substantially constant. Therefore, the thrust may be reducedfor landing without reducing the engine speed and it may be increased bya. decreasing of the exit area without having to accelerate the enginespeed, whereby acceleration of aircraft in the event of wave-off whencoming in for landing may be quickly effected.

With the tail cone at normal or cruising position and the turbineoperating at full speed, as indicated by the temperature line y, it willbe noted that the turbine inlet temperature is substantially lower thanthat corresponding to the line 0 for a turbo-jet plant having a nozzleor fixed exit area. The latter feature contributes to lower fuelconsumption and cruising operation of the turbine with lower outlettemperatures, thereby resulting in longer life of the apparatus.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so lmited, but is susceptibleof various changes and modifications without departing from the spiritthereof.

What is claimed is:

In jet propulsion apparatus, a turbine, means providing motive fluid forthe turbine and including a combustor furnished with fuel and suppliedwith air by a compressor driven by the turbine, a nozzle acting on theexhaust of the turbine to provide a, propulsion jet, said nozzleincluding a. component which is movable to vary the nozzle exit area tovary the jet thrust, a speed governor operated by the turbine forcontrolling the supply of fuel to the combustor and includingspeed-setting means, and mechanism for adjusting the speed-setting meansof the governor and the movable component of the nozzle and including amember movable to adjust the governor speed-setting means to increasethe fuel input to increase the turbine speed to maximum and then, whilemaintaining the turbine speed at maximum, movable to operate the movablecomponent of the nozzle to reduce the'nozzle exit area to increase thejet thrust.

ARNOLD H. BEDDING. DAVID W. HUTCHINSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

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